Malignant Mesothelioma Types

In biological terms, malignant mesothelioma is divided into three types: epithelial, sarcomatoid and biphasic. These classifications pertain to the shape and structure of the cancer cells.

Diagram of Malignant Mesothelioma Types.

Between 50 to 70 percent of malignant mesothelioma cases are epithelial, approximately 20 to 35 percent are biphasic, and 7 to 20 percent are sarcomatoid. Epithelial cells are marked by their well-defined and uniform shape and can closely resemble cells of another form of cancer known as adenocarcinoma. Sarcomatoid cells display an elongated spindle shape, which tend to be irregular rather than uniform in shape, and the cells often overlap one another. Cells of the biphasic variety contain both epithelial and sarcomatoid cells, which form in groups of like cells rather than displaying a uniform mixture.

Diagnosing what type of malignant mesothelioma a patient has can be challenging. One contributing factor is that it can be difficult to differentiate mesothelioma from adenocarcinoma, a cancer originating in glandular tissue, on small tissue specimens.

Mesothelioma ICD-9 Code

Pleural mesothelioma may also be referred to as ICD-9 code 163, a disease category and mesothelioma diagnosis code that represents malignant neoplasm of the pleura. Peritoneal mesothelioma may be called ICD-9 code 158, which accounts for malignant neoplasm of the retroperitoneum and peritoneum. Pericardial mesothelioma falls under the category ICD-9 code 164, which represents malignant neoplasm of the thymus, heart and mediastinum.